The immunity of COVID-19 survivors may last for DECADES for some – but it lasts only days for others and 11% never develop ANY protection against reinfection, the study suggests
- The researchers analyzed blood samples from 164 patients previously infected with COVID-19 in Singapore
- About 11% never had detectable levels of neutralizing antibodies, while about 55% had levels decreased in six months
- The remaining third had levels that had not fluctuated for at least six months and some had levels increased even after that period.
- Most patients had high levels of T cells, a type of white blood cell, even among the group that never had detectable neutralizing antibodies.
The duration of immunity to coronavirus after infection can vary widely from person to person, suggests a new study.
The researchers found that some individuals who had neutralizing antibodies against COVID-19 antibodies saw their levels decrease after just a few days or even a few weeks.
But at least a third of the participants had no change in levels after at least six months, and some even saw the levels rise, suggesting that their immunity could last for decades.
At least 10% have never had detectable levels.
The team, from Duke-NUS Medical School in Singapore, says the findings provide evidence that some previously infected patients are more likely than others to be reinfected during subsequent waves, or even by highly contagious variants.
A new study by Duke-NUS Medical School in Singapore found that 11% of COVID-19 survivors never had detectable levels of neutralizing antibodies (far left), while about 55% had levels decreasing within six months (according to left and center)
The remaining third had levels that had not fluctuated for at least six months and some had levels that increased even after that period. Photo: A patient is tested for coronavirus antibodies in Baldwin Park, California, February 2021
“The main message of this study is that the longevity of functional neutralizing antibodies against SARS-CoV-2 can vary widely and it is important to monitor this at an individual level,” said corresponding author, Dr. Wang Linfa, director of the Program on Emergency Diseases infectious diseases at Duke-NUS Medical School.
‘This work may have implications for the longevity of immunity after vaccination, which will be part of our follow-up studies.’
For the study, published in The Lancet Microbe, the team looked at 164 patients with COVID-19 in Singapore for six to nine months.
Each patient gave blood samples, which the researchers analyzed for neutralizing antibodies and T cells, which are a type of white blood cell that binds to viruses and kills them.
The data was then used to help create an algorithm to predict the trajectories of neutralizing antibodies over time.
Participants were classified into five groups depending on how long your antibodies against COVID-19 lasted.
The first group, called the ‘negative’ group, never had detectable neutralizing antibodies and constituted about 11.6 percent of the patients.
The following group, the ‘rapid decrease’ group, represented 26.6% of patients and had varying initial levels of antibodies that decreased rapidly, within a few days.
Then, the ‘slow decline’ group showed antibodies that disappeared in six months, constituting 29 percent of the participants.
The so-called ‘persistent’ group, made up of 31.7 percent of the participants, showed little change in their antibody levels for at least six months.
Finally, the delayed response group, 1.8 percent of patients, showed an increase in neutralizing antibodies during the study period.
However, the study found that most patients had high levels of T cells, even among those in the ‘negative’ group.
This implies that individuals can still be protected if they have a strong T cell response, despite low levels of neutralizing antibodies.
‘Our study examines neutralizing antibodies that are important in protecting against COVID-19. We found that antibodies against SARS-CoV-2 decrease in different people at different rates, ‘said the corresponding author, Dr. David Lye, director of the National Center for Infectious Diseases in Singapore.
‘This emphasizes the importance of public health and social measures in the ongoing response to a pandemic outbreak.
‘However, the presence of T-cell immunity offers hope for long-term protection, which will require further studies and time for confirmation of epidemiological and clinical evidence.’